Laundering adjunct and method of preparing



United States Patent 3,424,545 LAUNDERING ADJUNCT AND METHOD OFPREPARING Robert Andrew Bauman, New Brunswick, NJ, assignor toColgate-Palmolive Company, New York, N.Y., a corporation of Delaware NoDrawing. Filed Mar. 9, 1966, Scr. No. 532,902

US. Cl. 8-437 3 Claims Int. Cl. C02b 5/06; D06f 35/00 ABSTRACT OF THEDISCLOSURE A home laundering process using van aqueous detergent whichprovides the presence of phosphorylated cellulose (containing about 5.3%phosphorus) in the Wash cycle to sequest the calcium and magnesium ionsin the water.

The present invention relates to sequestering calcium and magnesium ionsin home laundering and, more particularly to a laundering adjunct, amethod of preparing said adjunct, and to a method of using said adjunctin home laundering.

The effect of water-soluble calcium and magnesium salts in the waterused in laundering or in personal ablutions has been recognized sowidely it hardly seems necessary to refer to it. For commerciallaundries commercial water-softening units and regenerating facilitiesare available. For the home laundry similar regenerable Watersofteningunits are available. However, the use of the home-size regenerablewater-softening units is not universal and, in fact, in many localitiessuch Water-softening units are not available or are beyond thecomprehension of a large portion of the population.

To overcome these difficulties and to make a better product themanufacturers of detergents and soap powders and even the manufacturersof both salts have incorporated in their products exhaustible agentssuch as the so-called inorganic detergency builders.

The role of the inorganic builder in improving the performance of adetergent formulation is of the highest importance, but the mode ofaction is still not clear. A number of functions have been suggested forit, including suspending of particulate soils, lowering the criticalconcentration of the detergent, increasing the Wetting rate, influencingthe degree of adsorption of surfactant on textile fibers, effecting theelectrostatic charge of soil and fabric, and others but the majoreffects are usually attributed to the water softening ability of theinorganic builder.

Formulation of a detergent to take care of all of the hardness in thewater used in the wash step of the laundry cycle is not diflicult exceptin the case of liquid detergents where it is a real problem to combinethe necessary quantities of detergent, builder, and other essentialingredients into a compatible mixture occupying a reasonable finalvolume. In this case an alternate method for achieving the benefits of abuilder would be a boon to the formulator and manufacturer.

Since at present the inorganic builder or other watersoftening agent isincorporated in the detergent, a part of the detergent formulation andwater-soluble, it is available only during the wash step and not duringthe rinse step or steps of the laundering cycle. It has been shown thatthe residual-soil build-up on repeatedly laundered cotton can be removedby a rinse containing ethylene diamine tetraacetate (EDTA) which is anindication of the desirability of maintaining a useful concentration ofwater-softening agent during the rinse portion of the laundering cycleas well as during the wash portion thereof.

Thus, it is apparent that the present means of overcoming thedisadvantages of the variation of the hardness of the water in variousparts of the World are (1) limitation of the formulation of liquiddetergents; (2) the absence of Water-softening agent in the rinse cycle;and (3) the relative complexity of the regeneration operation of homewater-softening units. The present invention overcomes all of thesedisadvantages.

At the present time the generally used water-softening agentsincorporated in home laundering detergents are complex phosphates suchas sodium tripolyphosphate, i.e., penta-sodium tripolyphosphate, andpotassium pyrophosphate. The present invention provides a launderingadjunct to be used in conjunction with detergents containing inorganicbuilder or in conjunction with detergents substantially devoid ofinorganic builder in the washing step and in the rinsing step of a homelaundering cycle and in some forms for use in personal ablutions.

Accordingly, it is an object of the present invention to providewater-insoluble geometric solid comprising cation-exchange materialsuitable for contact with washand rinse-water during both portions of ahome laundering cycle. It is a further object of the present inventionto provide a water-insoluble foraminous sheet of fibrous material havingcation-exchange capabilities. It is also within the purview of thepresent invention to provide the inner periphery of a home launderingmachine or the dasher thereof with a continuous or discontinuous surfaceof cation-exchange material bonded to the structural material byWater-insoluble material. It is a preferred object of the presentinvention to provide phosphorylated cellulose having water-softeningcapabilities for contact with washand rinse-water in both the washportion and the rinse portion of home-laundering cycle. It is also anobject of the present invention to provide a method of using suchwaterdnsoluble cation-exchange materials in both the wash and rinseportions of a homelaundering cycle. The present invention provides amethod of preparing phosphorylated cellulose for use as aWater-softening agent in the wash and rinse portions of ahome-laundering cycle. A method regenerating a phosphorylated cellulosewater-softening material is likewise an object of the present invention.

It is to be observed that, while industrial size watersoftening plantsemploying zeolites have been available for at least forty years,cation-exchange resins have been available for at least twenty years,and domestic watersoftening units have been available for'at leastfifteen years, no one has suggested that the growing children in a homecan have the advantage of the presence of calcium salts in the potablewater of the domestic environment and the home laundress can have theadvantage of soft water by the method of the present invention In 1956US. Patent No. 2,749,306 issued to W. B. Coleman in which was discloseda method of regenerating water-softening ion-exchange materialsincluding the removal of iron salt deposits. The patentee found thatalkali metal phosphates were very useful for the regeneration ofion-exchange material and particularly recommended the alkali metalpyro-, poly-, and metaphosphates and acid phosphates or mixtures of theforegoing for that purpose. The preferred phosphates Were the alkalimetal tripolyphosphates, such as sodium tripolyphosphate, and thepyrophosphates such as sodium acid pyrophosphate.

While the early development of ion-exchange materials was directedprimarily to the use of zeolites, however, in 1931 US. Patent No.1,793,670 issued to G. Borrowman disclosing an ion-exchange organicmaterial comprising lignite or brown coal having exchangeable alkalimetal. Further development of organic ion-exchange material is evidencedby the issuance of US. Patent No. 2,148,970 disclosing a process ofliquid purification by contacting the liquid with a water insolublesolid cyclic organic compound having an imino group within the ring andadjacent thereto an atom which is double bonded to a third atom.

In 1940 U.S. Patent No. 2,195,196 issued to H. Wassenegger et al.disclosing a method for diminishing the swelling of phenol resins inaqueous solutions. The resinous gel produced by condensing a phenolicbody with more than a molar equivalent of an aldehyde is subjected to anafter-treatment with a large quantity of hot concentrated hydrochloricsulfuric or phosphoric acid. In 1940 US. Patent No. 2,204,539 issued toH. Wassenegger et al. which was directed to a method of effectingcationexchange employing a water-insoluble resin of an aldehyde and amember of the group consisting of naphthalene, acenaphthene,hydroxybenzene, and phenanthrene containing nuclear sulfonic acidgroups.

In US. Patent No. 2,340,111 an ion-exchange resin comprising infusible,insoluble copolymer containing carboxyl groups is disclosed. In US.Patent No. 2,366,007 sulfonated, cross-linked, insoluble, infusiblepolymerizates of polyvinyl aryl compounds are disclosed for use inremoving cations from liquid media, especially aqueous media. Thecation-exchange resin disclosed in US. Patent No. 2,373,547 is theinfusible resinous reaction product of phenol, formaldehyde, and analiphatic amino-carboxylic acid. In the companion US. Patent No.2,373,549 a resin having high cation capacity comprising a phenol,aldehyde, nitrourea reaction product is described. The disclosure of US.Patent No. 2,611,337 is concerend with cellulosic nitrogen andphosphorous-containing materials having the property of exchangingcations in aqueous solutions. A method removing cations from wateremploying substantially spherical beads having diameters in the range of0.3 to 1.0 millimeter comprising the reaction product of methacrylate,divinylbenzene, and methacrylic anhydride has been disclosed.

In US. Patent No. 2,933,460 issued in 1960 to GA. Richter, Jr. et al.ion-exchange fibers having at least one small dimension of the order ofone-tenth to twenty mils are described. These fibers comprise across-linked polymer of a linear addition polymer at least seven molpercent of the units containing ion-exchange groups such as carboxylgroups, sulfonic groups, phosphoric acid groups, and thiol groups forcation-exchange. A companion US. Patent No. 2,974,101 provides adescription of improved ion-exchange assemblies and of methods oftreating liquids particularly assemblies comprising filamentousstructures. Similar to the latter patent is the disclosure of US. PatentNo. 3,062,379 which is directed to fabricated ion-exchange fiberconstructions in which relatively short sections of ion-exchange fibersare attached to a supporting base composed in whole or in major part ofwater-insoluble materials Which do not exhibit ion-exchange properties.

The further disclosure of fiber-form ion-exchange materials is providedin U.S. Patent No. 3,097,051. These fiber-form ion-exchange materialsnative fiber cellulose is reacted in a system comprising trifluoroaceticanhydride, a suitable inert non-aqueous solvent or diluent and themono-anhydride of a tricarboxylic non-aqueous organic acid whichcontains one free, active carboxylic group in addition to the carboxylicgroups involved in the cyclic anhydride structure.

In US. Patent No. 2,609,360 it is stated that water-soluble phosphatesof polyvinyl alcohol are produced by the reaction of polyvinyl alcoholwith urea phosphate. These are capable of self-polymerization, whenheated without the aid of a catalyst, to form high-capacity ion-exchangesubstances.

In Textile Research Journal for January, 1949, J. F. Jurgens, J. DavidReid, and J. Dv Guthrie published a paper entitled Phosphorylated CottonCellulose as a Cation-Exchange Material. The essence of the publicationis that phosphorylated cotton cellulose made by the phosphoric acid-urea(see US. Patent No. 2,482,755) has a high cation-exchange capacity andwhen used in the form of a coarse fabric it shows good flowcharacteristics in the calcium-hydrogen cycle. Its cation-exchangecapacity increases with increasing phosphorus content and at aphosphorus content of about five percent the cation-exchange capacityreaches about 1,000 milliequivalents per kilogram. It is possible thatspecialized uses may be found for phosphorylated cotton cellulose,especially in the cotton form. Subsequently, I. D. Guthrie published anarticle in Industrial and Engineering Chemistry (Vol. 44, No. 9)entitled Ion Exchange Cottons in which the preparation ofcation-exchange cottons is described. The product was made by the methoddescribed in US. Patent No. 2,482,755 by curing cotton with a mixture ofphosphoric acid and urea. Sulfoethylated cotton, partiallycarboxymethylated cotton, and the succinic acid half ester of cottoncellulose, all having cotton-exchange capabilities, are also described.Continuous Ion Exchange With an Endless Belt of Phosphorylated Cotton isthe title of an article published in the March 1955 issue of Industrialand Engineering Chemistry.

In spite of all of the investigations of cation-exchange material in thelast two decades no one has suggested a simple method of applying theprinciples of cation-exchange to home laundering operation. The presentinvention provides (1) for hanging a cation-exchange fabric in atraditional tub used for hand washing and/ or rinsing or in the modernautomatic washing machine during both the wash and the rinse portions ofthe laundering cycle; (2) for coating in any suitable manner theperiphery of the traditional tub used for hand washing and rinsing orthe periphery of the tub of a modern automatic washer in a continuous ordiscontinuous form with cation-exchange material; (3) for coating in anysuitable manner in a continuous or discontinuous fashion the exterior ofthe dasher of an automatic washing machine; and (4) for suspending inthe traditional tub used for hand laundering or in the modern automaticwasher during both the wash and rinse cycles a porous container chargedwith particulate cation-exchange material and for personal ablutions awash-cloth comprising two layers of terry cloth and an interposed layerof fabric having cation-exchange capabilities.

It is to be observed that the ion-exchange capacity of ion-exchangematerials is not the same. Guthrie in Tex. Res. J. 20, 617 (1950) andInd. Eng. Chem. 44, 2188 (1952) examined the capacities for the exchangeof hydrogen for sodium atoms (but not for calcium binding) of cottonupon which ion-exchange properties had been conferred in several ways.The results are summarized in Table I.

TABLE I Material: Capacity in meq./g. Phosphorylated cellulose 2.56Sulfethoxy cellulose 0.340 Carboxymethyl cellulose 0.248

Succinic acid half ester of cellulose 0.247

1 Milliequivalents per gram. I

These data clearly show that for the exchange of hydrogen for sodium thecapacity of phosphorylated cellulose is about seven and one-half to tentimes that of the other materials or 750 to 1000 percent that of theother cellulosic materials.

Illustrative of the principles of the present invention is thepreparation of phosphorylated cellulose to provide a cation-exchangematerial, and the use of the so-produced cation-exchange matreial tosequester calcium ions under conditions comparable to those existing inhome laundering.

Preparation of phosphorylated cotton containing 5.3% of phosphorus A 24x 6 inch strip of Indianhead cotton was evenly impregnated with asolution of 13.5 grams of urea and 6 grams of 86% phosphoric acid in 16milliliters of water. This amount of solution was just sufficient toimpregnate the cloth. The cloth was air-dried in a horizontal positionand then heated for thirty minutes at about 140 to 150 C. (about 285 toabout 305 F.) in a gravity convection oven. The treated cloth was washedrepeatedly in deionized water, dilute aqueous sodium hydroxide, waterand then air-dried. The treated cloth so obtained is nearly white, buthas a rougher, heavier hand than the original cloth, and, when wet, ithas a slippery feel. Under agitation of a Terg-O-Tometer run the clothfrays badly at the edges. For the detergency tests three ways ofpreventing the disintegration were employed to wit: (1) phosphorylatinga sulfone-crosslinked cotton fabric instead of Indianhead cotton (Test1); (2) painting the edges with a label varnish (Test 2) and (3) hemmingthe four edges (Test 3). Cotton crosslinked with Ganalok A-14 (sulfonecrosslinked cotton) was phosphorylated satisfactorily to a product ofmarkedly greater strength than Indianhead cotton, but its capacity forcalcium was much lower. The varnished edge cloth successfully withstoodthe agitation of the Terg-O-Tometer machine, but its calcium capacitywas reduced out of proportion to the actual area covered by the varnish.Hemming proved to be the preferable protective treatment.

Assuming that the reaction which occurs is the conversion of thehydroxyl groups of cellulose to phosphoric ester groups, OPO(ONa) thenthe sample of phosphorylated Indianhead cotton which was found tocontain 5.3 percent of phosphorus represents a ten percent conversion ofthe available hydroxyl groups of the cotton to phosphoric ester groups.The capacity of the cloth containing 5.3 percent of phosphorus is about30 milligrams of calcium per gram of cloth.

Calcium binding capacity The capacity of the so-produced phosphorylatedcotton to bind calcium was measured by agitating a weighed piece of thecloth in an aqueous solution of calcium chloride of known concentrationand then determining the depletion of calcium ions in the solution bytitration of an aliquot with standard ethylene diamine tetraacetatesolution. [Betz, Handbook of Industrial Water Conditioning, 5th Ed. BetzLaboratories Inc., (1957)].

The time required for the phosphorylated cotton to bind calcium to itsfullest capability was dependent on the physical form, being fast foropen textured cotton gauze and slow for the more tightly wovenIndianhead fabric. Although for the latter material as much as 24 hoursmight be required for completion of the reaction, the rate of thereaction, as might be suspected, slows down considerably during thistime so that most of the calcium binding occurs in an initial shortperiod. One can, therefore, speak of a practical calcium bindingcapacity of the cloth meaning the calcium removed from solution duringsome arbitrary time period comparable to that encountered in launderingpractice. In the following table is shown the time dependence of calciumbinding by triplicate pieces of cloth each immersed in one liter ofcalcium chloride solution containing 60 mg. calcium ion-this isequivalent to 150 p.p.m. (as CaCO hard water.

TAB LE II Mg. calcium bound Time A B C 24 hours- 59 59 59 To determinewhether the capacity is dependent on the concentration of calcium, equalweights of phosphorylated cotton (sulfone-crosslinked cotton in thiscase) were agitated for one hour in solutions of calcium chloridevarying in concentration from 0.008 to 0.013 M (-1300 p.p.m. as CaCO butin which the same total quantity of calcium was present. In each casethe weight of calcium bound by the cloth was the same, indicating thatit is the amount of calcium which is important and not itsconcentration.

Since substantially all soap powders contain sodium and/or potassium,e.g., in one commercial product 0.013 molal sodium and in another 0.003molal sodium plus potassium the effect of sodium ion upon the capacityof the phosphorylated cotton to bind calcium was examined by agitatingpieces of sulfone-crosslinked phosphorylated cotton weighing 300milligrams in 25 milliliter portions of an aqueous solution containingvarying amounts of sodium chloride and being 0.0126 molal to calciumchloride. The data presented in Table III clearly shows that atconcentrations if sodium in the range usually existing in commercialdetergents the interference of the sodium ion is not a serious factor inpractice.

The regenerability of a calcium binding cloth will depend at least inpart on the kind of reactive groups that it possesses. Thus, fromrecorded experience with ion exchange resins of varying types the easeof regeneration could be expected to vary from excellent with sulfonicacid groups to poor with carboxyls and of some intermediate characterwith phosphorus acid groups. In practice it was found that a 20%solution of sodium tripolyphosphate would restore all the calciumbinding activity of exhausted phosphorylated cotton, but a sizableportion of the activity could be regained by the use of even 0.1% ofthis reagent. This was demonstrated repeatedly in an experiment in whichthree similar pieces of phosphorylated cotton (M, D, E) and one piece ofuntreated cotton (P) were alternately agitated in a Terg-O-Tometer withcalcium chloride solution and with a 0.05% solution of sodiumtridecylbenzenesulfonate containing for M, no other reagent; for P andD, 0. 1% NaTPP; and for E, 0.2% Na 'ITPP. Between treatments were rinseswith deionized water. The remaining hardness of the calcium chloridesolutions was determined after treatment with the cloth by EDTAtitration, and the results in p.p.m. (as CaCO hardness removed from theoriginal p.p.m. water are tabulated below.

TABLE IV Phosphorylated cotton sample P M D E Regenerating solution:

Sodium tridecylbenzenesulfonate,

percent 0. 05 0. 05 O. 05 0.05 Pentasodium tripolyphosphate,

percent 0. 1 0. 2 P.p.m. of hardness removed by clothz' Originally 0 7979 78 After saturation with calcium. 0 1 2 0 After wash 0 5 58 71 Aftersaturation wit cclaiurn. 0 0 1 0 After wash 0 0 54 66 Do 0 5 62 75*P.p.m.parts per million (parts per 10 It is evident that (1) untreatedcotton (P) shows no calcium binding properties, 2) once the treatedcloth has been saturated with calcium its activity cannot be restored bywashing in 0.05% NaTBS alone, and (3) the relatively dilute solutions ofNaTPP, similar to what would be present in the wash Water duringlaundering, can restore a surprisingly large amount of capacity. Theseexperiments were run in deionized water; additional NaTPP would benecessary to take care of any hardness in the water that would be usedin a practical application of this procedure.

Statistically controlled detergency tests were run in which it waspossible to demonstrate a beneficial effect of a calcium binding clothon detergency.

The test chosen was one in which a panel of eight persons each wiped hisface and neck with four 4 /2 x 6 inch swatches of Indianhead cotton (twoof these in the morning and two in the afternoon of the same day) forwhich instrumental reflectance readings were obtained before and aftersoiling. These swatches, separated into four lots drawn one from eachpanel member, were washed in various solutions in the four buckets of aTerg-O-Tometer for twenty minutes at 120 F. and 100 r.p.m. agitation,rinsed, pressed, and the reflectance again read.

This procedure was repeated twice more, the difference between the finalreflectance reading and the initial reading on the fresh cloth beingtaken as the Residual Soil. Throughout these tests 0.05% sodiumtridecylbenzenesulfonate was used in every bucket. The NaTPP used wasWestvaco anhydrous commercial grade of 95% purity. All wash solutionswere adjusted to pH before use.

FIRST DETERGENCY TEST Object To measure the effect on detergency ofphosphorylated cotton in the absence and presence of sodiumtripolyphosphate.

Conditions Phosphorylated crosslinked cotton with capacity of 50 mg. Caor the equivalent of one liter of 125 p.p.m. (as CaCO hard water; 100p.p.m. water for wash and rinse (made from CaCl Results Residual soilSignificance,

percent Treatment (1) Detergent alone 14. 41 95 (2) Detergent-l-PC.11.48

(3) Detergent+NaTPP(.045%) 4. 52 (4) Detergent+NaTPP+RG 4. 26

*P.C. =pl1osphory1ated cotton.

Conclusions The phosphorlyated cotton is effective in reducing residualsoil buildup. There is a small improvement when RC. is present inaddition to NaTPP.

SECOND DETERGENCY TEST Object Phosphorylated Indianhead cotton (withedges protected by Varniton V-2lB Label Varnish) with capacity of 38 and56 mg. Ca or equivalent to one liter of 95 and 140 p.p.m. hard water;100 p.p.m. hard water for was-h, deionized water for rinse.

Results Treatment Residual soil Significance,

(percent) (1) P. C. for 95 p.p.m. hardness 90 (2) P. O. for 140 p.p.m.hardness 5. 94 99 (3) P. C. as in 1+O.l% NagSOt 3. 81 9S) (4) P. O. asin 2, and ten minutes pretreatment of wash solutions 3. 84

Conclusions All three variations yield improved performance ofphosphorylated cotton. Ranked in order of decreasing importance they are(1) added electrolyte, (2) pretreatment of Wash solution, and (3)increased capacity of PC.

THIRD DETERGENCY TEST Object To determine whether a combination of allthree factors found individually to improve the performance ofphosphorylated cotton will give detergency building equivalent to thatof sodium tripolyphosphate.

Conditions Phosphorylated Indianhead cotton with hemmed edges withcapacity of 60 mg. and 15 0 mg. Ca or equivalent to one liter of p.p.m.and 385 p.p.m. hard water; 150 p.p.m. hard water for wash, deionizedwater for rinse;

fifteen minute pretreatment of Wash solution with RC.

Results Treatment Final Residual Significance Hardness Soil percentp.p.m.

(1) 0.1 NazSOt 131 6. 11 (2) Na2SO4+P.C. for 150 p.p.m. hard- 99 36 3.03 ness 10 2.65 70 (4) 0.075% NaTPP l 1.89

1 Average of three runs. 2 Phosphorylated Cotton.

' Conclusions These data obtained in a statistically-controlled Terg-O-Tometer test show that calcium ions are bound by phosphorylated cottonunder washing conditions and that the performance approaches that ofsodium tripolyphosphate as measured by residual soil on the swatchesafter the three cycles.

These data also establish that after saturation with calcium ions thephosphorylated cotton, i.e., the exhausted cation-exchange material, canbe regenerated by soaking in pentasodium tripolyphosphate solutionhaving a concentration of NaTPP as low as one percent.

The simplest form of a home laundering insoluble regenerable sequestererfor calcium and magnesium, i.e., a cation exchange material, is anon-ravelling cloth having an area of at least about one square footimpergnated with a water-insoluble material having alkaline earthbinding groups, e.g., carboxylic and/or sulfonic and/or phosphoric acidgroups. The phosphorylated cotton described and discussed herein beforeis illustrative of this embodiment of the present invention. Since thecapacity of phosphorylated cotton containing about 5.3 percent ofphosphorus is about 30 milligrams per gram and since 60 milligrams ofcalcium per liter is a hardness of about 150 p.p.m. it is a simplemathematical computation, knowing the volume of the tub or automaticwasher and the hardness of the water used, to calculate forphosphorylated cotton the size or weight of cation-exchange materialrequired to have a practical affect upon the sequestration of cations inthe water employed in the wash and/or rinse portion of the launderingcycle. For example, with phosphorylated cotton containing 5.3 percent ofphosphorus having a calcium binding capacity of 30 milligrams per gramof cloth and water having a hardness equivalent (as CaCO to 150 p.p.m.or 60 milligrams per liter, i.e., about 227 milligrams per gallon, about7.6 grams of the phosphorylated cotton per gallon of water is used. Withsimilar knowledge of the sequestering power of other cation-exchangematerials the amount required can be readily calculated. Consequently,for the phosphorylated cotton described hereinbefore for use in the washand the rinse portions of the laundering cycle without regenerationbetween the wash and rinse portions of a laundering cycle consisting ofa wash portion and two rinse portions each employing 17 gallons of waterhaving a hardness of 150 p.p.m., about 386 grams of phosphorylatedcotton is used with regeneration with TPP solution of at least onepercent concentration after each laundering cycle. When TPP or otherregenerant is present in the wash portion of the laundering cycleregeneration is less frequent. For improved results the water used ineither the wash portion or the rinse portion or in both portions of thelaundering cycle is pretreated with phosphorylated cotton, of highertahn the minimum required, in the presence of a neutral electrolyte,e.g., sodium sulfate.

Many persons prefer to perform their ablutions using soft water. Forthose forced to use hard water, a wash cloth comprising a sandwich ofterrycloth, for example, with cation-exchange material, for examplephosphorylated cotton interposed between two layers of terrycloth andhemmed around the edges solves the problem in a simple manner.

In another embodiment of the present invention particulatecation-exchange material is charged to a porous container, e.g., aloosely woven bag with a draw-string closure, which charged container isattached to the water inlet of an automatic washer or suspended thereinin any other suitable manner.

In still another embodiment of the present invention a portion or thewhole of the inner periphery of tub of a washing machine is coated witha water-insoluble adhesive and then coated with particles ofcation-exchange material or with a layer of cation-exchange fabric.Alternatively, the plunger or dasher can be so treated and when desiredboth the dasher and the inner periphery of the tube are so treated.

It is manifest that the incidence of regeneration of the Water-insolublecation-exchange material is dependent upon (1) the hardness of the wateremployed, i.e., the milligrams of cation to be removed per gallon ofwater; (2) the volume of water employed; (3) the cation-binding capacityof the cation-exchange material per gram; and (4) the quantity or weightof cation-exchange material employed.

Those skilled in the art will understand that when a detergency buildersuch as pentasodium tripolyphosphate is present in the detergent formulathat a mobile equilibrium is established and the incidence ofregeneration of the cation-exchange material is less frequent.

Heavy duty liquid detergent formulations have always had two majordrawbacks in attaining a sizeable share of the market; one is cost andthe other is their failure to measure up to the performance of powdereddetergents especially in hard water. The major factor in the failure ofheavy duty liquids to achieve performance parity with powders is thedifference in builder content. Solubility limits have set the buildercontent in liquids at about 20% while powders incorporate approximately50% builder. Detergent raw material suppliers as well as detergentformulators have been aware of the problem.

The advantage in liquid detergent formulation provided by the conjunctuse of cation-exchange material in the wash portion of the homelaundering cycle can be illustrated by consideration of the formulationof a presently sold liquid detergent composition.

Alkanolamides 2 10 Potassium pyrophosphate 15 Potassium xylene sulfonate8 Optical brightener, color, suspending agents, perfume, impurities,etc. 3.5 Water 56.5

Of this formulation it is specified that one-half cup (or grams) be usedfor a washing machine load comprising about 17 gallons of water. Sinceone mole of potassium pyrophosphate will complex just under one mole ofcalcium ions, the maximum hardness of water that could be completelysoftened by the specified amount of the above formulation is 100 p.p.m.Since it is not feasible to increase the potassium pyrophosphate contentof the formula to more than about 20% without seriously reducing theamount of organic detergent, water of hardness greater than p.p.m. willnot be adequately softened. Therefore, the use of a cation-exchangematerial in conjunction with the detergent formulation as presently madewill provide additional softening capacity for water of greater hardnessand/ or additional softening capacity for the rinses. Alternatively,part or all of the pyrophosphate could be eliminated from the detergentformulation (as well as the potassium xylenesulfonate which is presentas a solubilizing or hydrotroping agent) and water softening achievedlargely or solely by the adjunct cation-exchange material thuspermitting a greater concentration of organic detergent to beincorporated in the detergent formulation should that be regarded asdesirable; for example, the use of more compact packaging for equaleffectiveness of product.

Similarly the concentration of detergency builder can be reduced whenthe solid detergent formulation is used in conjunction withcation-exchange material in the wash portion of the home-launderingcycle. It is present practice to prepare built laundry detergents with aminimum of inorganic builder, such as pentasodium tripolyphosphate(NaTPP), of 25 percent and as much as 50 percent. When thecation-exchange material is used as provided in the present inventionthe TPP can be reduced or even eliminated.

Those skilled in the art will recognize that the foregoing is adescription of the use of an adjunct in the wash and/ or rinse portionsof the home-laundering cycle. Hence, the present invention provides amethod of home-laundering in which the amount of soiled cloth washed atone time does not exceed about twelve to fifteen pounds and the volumeof water employed in any portion of the cycle does not exceed about 17gallons, wherein the water employed, at least in the wash portions ofthe laundering cycle, is contacted with an amount of cation-exchangematerial effective to reduce the concentration of calcium in and,preferably, to remove substantially all of the calcium from the wateremployed. It is presently preferred to make the cation-exchange materialavailable to the home-launderer in a unit requiring regeneration afteruse in a single laundering when using water of maximum hardness and atless frequent intervals when using water of less than said maximumhardness.

What is claimed is:

1. In the method of home-laundering wherein in a wash step soiled fabricis contacted with water containing a detergent, wherein the washedfabric is separated from the water and in at least one rinse step of thelaundering cycle the washed fabric is contacted with water free fromdetergent, and in a final step of the laundering cycle the rinsed fabricis separated from the rinse water, the improvement which comprisescarrying out at least the wash step in the presence of a water-insolublecation-exchange phosphorylated cellulose material containing about 5.3%phosphorus.

2. In a method as defined in claim 1 the improvement wherein the cationexchange material is phosphorylated cotton.

3. In a method as defined in claim 2 the improvement 1 1 wherein thephosphorylated cotton has a calcium binding capacity of 30 milligrams ofcalcium per gram of cation exchange material.

References Cited UNITED STATES PATENTS 1 2 FOREIGN PATENTS 838,9736/1960 Great Britain.

MAYER WEINBLATT, Primary Examiner.

US. Cl. X.R.

